Nothodissotis Veranso-Libalah & G.Kadereit, 2019

Veranso-Libalah, Marie Claire, Lachenaud, Olivier, Stone, Robert Douglas & Kadereit, Gudrun, 2019, Nothodissotis (Melastomataceae), a new genus from Atlantic Central Africa, including the new species N. alenensis from Equatorial Guinea, PhytoKeys 118, pp. 89-103 : 91-92

Nothodissotis Veranso-Libalah & G.Kadereit gen. nov.

Type.

Nothodissotis barteri (≡ Dissotis barteri Hook. f.)

Morphological diagnosis.

Nothodissotis species resemble Dissotis by their 5-merous flowers, calyx with caducous lobes and tube not accrescent on the fruit, presence of intersepalar appendages, dimorphic stamens with the connective bearing bipartite ventral appendages and a well-developed pedoconnective, anthers opening by an introrse apical pore, and cochleate seeds. They differ by being deciduous shrubs (vs. evergreen shrubs and herbs) and having the calyx-lobes notched at apex and asymmetrical (vs. entire and symmetrical); the latter character is unique within African Melastomateae.

Description.

Deciduous, ramose shrubs, 1.5-4 m tall; stems 4-angular to cylindrical, glabrous or strigillose; internodes short, nodes setulose or strigillose (Figs 2 , 3 ). Leaves elliptic with appressed hairs on both sides; 3-5-nerved from the base, margins entire or minutely serrulate. Inflorescences terminal, with 1 –7(– 15) flowers, flowers 5-merous, pedicellate, subtended by a pair of caducous short ovate bracts. Hypanthium broadly urceolate, with scattered appendages, these either sessile and penicillate ( N. alenensis ; Fig. 2 ) or stipitate and bearing a stellate crown of hairs at their apex ( N. barteri ; Figs 2 , 3 ). Intersepalar appendages present, similar to hypanthial appendages but much larger, and caducous (Fig. 2 A–D ). Calyx-lobes contorted in aestivation and completely concealing the floral buds, elliptic to obovate, asymmetrically notched and bearing penicillate hairs at apex, uniformly pubescent outside, caducous. Petals mauve, broadly obovate, glabrous except for the ciliate margin. Stamens 10, dimorphic in size but not in colour, pedoconnective well-developed, connective with bipartite ventral appendage, anther falcate, opening by an introrse apical pore. Ovary with a crown of persistent bristles, style simple, linear, glabrous. Fruits capsular, enclosed within the hypanthium, splitting loculicidally in 5 valves, the seeds attached on placentas borne on a central column. Seeds (only known in N. barteri ; see Fig. 2 E–H ) cochleate, exarillate, with parallel rows of tubercles.

Etymology.

Derived from the Greek word ‘nothos’ ' meaning false, and Dissotis , the genus which Nothodissotis most closely resembles.

Distribution and habitat.

Nothodissotis includes two species in Atlantic Central Africa, both of which are restricted to rocky outcrops within the equatorial rainforest zone (Fig. 4 ).

Key to the species of Nothodissotis

Figures

Figure 2. Digital microscope photographs of the hypanthia of Nothodissotis spp. (A-D) and SEM photographs of the seeds of N. barteri (E-H). A, B hypanthium of Nothodissotis alenensis (Parmentier & Esono 3453); cl = calyx-lobes and ia = intersepalar appendages C, D hypanthium of N. barteri (Ngok Banak 1196) E, F seeds of N. barteri in dorsal view G, H same in lateral view (Parmentier 3544).

Figure 3. Nothodissotis barteri. A habit B branches and inflorescence C leaf seen from above, and flower (petals fallen) D flower bud E blooming flower F stamens. From Droissart et al. 1668 (A, B) and Stevart & Oliveira 5136 (C-F).

Figure 4. Distribution of Nothodissotis species.